1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1982, 1986, 1989, 1990, 1991, 1993 5 * The Regents of the University of California. 6 * (c) UNIX System Laboratories, Inc. 7 * Copyright (c) 2000-2001 Robert N. M. Watson. 8 * All rights reserved. 9 * 10 * All or some portions of this file are derived from material licensed 11 * to the University of California by American Telephone and Telegraph 12 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 13 * the permission of UNIX System Laboratories, Inc. 14 * 15 * Redistribution and use in source and binary forms, with or without 16 * modification, are permitted provided that the following conditions 17 * are met: 18 * 1. Redistributions of source code must retain the above copyright 19 * notice, this list of conditions and the following disclaimer. 20 * 2. Redistributions in binary form must reproduce the above copyright 21 * notice, this list of conditions and the following disclaimer in the 22 * documentation and/or other materials provided with the distribution. 23 * 3. Neither the name of the University nor the names of its contributors 24 * may be used to endorse or promote products derived from this software 25 * without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 37 * SUCH DAMAGE. 38 */ 39 40 /* 41 * System calls related to processes and protection 42 */ 43 44 #include <sys/cdefs.h> 45 #include "opt_inet.h" 46 #include "opt_inet6.h" 47 48 #include <sys/param.h> 49 #include <sys/systm.h> 50 #include <sys/acct.h> 51 #include <sys/kdb.h> 52 #include <sys/kernel.h> 53 #include <sys/lock.h> 54 #include <sys/loginclass.h> 55 #include <sys/malloc.h> 56 #include <sys/mutex.h> 57 #include <sys/ptrace.h> 58 #include <sys/refcount.h> 59 #include <sys/sx.h> 60 #include <sys/priv.h> 61 #include <sys/proc.h> 62 #ifdef COMPAT_43 63 #include <sys/sysent.h> 64 #endif 65 #include <sys/sysproto.h> 66 #include <sys/jail.h> 67 #include <sys/racct.h> 68 #include <sys/rctl.h> 69 #include <sys/resourcevar.h> 70 #include <sys/socket.h> 71 #include <sys/socketvar.h> 72 #include <sys/syscallsubr.h> 73 #include <sys/sysctl.h> 74 75 #ifdef REGRESSION 76 FEATURE(regression, 77 "Kernel support for interfaces necessary for regression testing (SECURITY RISK!)"); 78 #endif 79 80 #include <security/audit/audit.h> 81 #include <security/mac/mac_framework.h> 82 83 static MALLOC_DEFINE(M_CRED, "cred", "credentials"); 84 85 SYSCTL_NODE(_security, OID_AUTO, bsd, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 86 "BSD security policy"); 87 88 static void crfree_final(struct ucred *cr); 89 static void crsetgroups_locked(struct ucred *cr, int ngrp, 90 gid_t *groups); 91 92 static int cr_canseeotheruids(struct ucred *u1, struct ucred *u2); 93 static int cr_canseeothergids(struct ucred *u1, struct ucred *u2); 94 static int cr_canseejailproc(struct ucred *u1, struct ucred *u2); 95 96 #ifndef _SYS_SYSPROTO_H_ 97 struct getpid_args { 98 int dummy; 99 }; 100 #endif 101 /* ARGSUSED */ 102 int 103 sys_getpid(struct thread *td, struct getpid_args *uap) 104 { 105 struct proc *p = td->td_proc; 106 107 td->td_retval[0] = p->p_pid; 108 #if defined(COMPAT_43) 109 if (SV_PROC_FLAG(p, SV_AOUT)) 110 td->td_retval[1] = kern_getppid(td); 111 #endif 112 return (0); 113 } 114 115 #ifndef _SYS_SYSPROTO_H_ 116 struct getppid_args { 117 int dummy; 118 }; 119 #endif 120 /* ARGSUSED */ 121 int 122 sys_getppid(struct thread *td, struct getppid_args *uap) 123 { 124 125 td->td_retval[0] = kern_getppid(td); 126 return (0); 127 } 128 129 int 130 kern_getppid(struct thread *td) 131 { 132 struct proc *p = td->td_proc; 133 134 return (p->p_oppid); 135 } 136 137 /* 138 * Get process group ID; note that POSIX getpgrp takes no parameter. 139 */ 140 #ifndef _SYS_SYSPROTO_H_ 141 struct getpgrp_args { 142 int dummy; 143 }; 144 #endif 145 int 146 sys_getpgrp(struct thread *td, struct getpgrp_args *uap) 147 { 148 struct proc *p = td->td_proc; 149 150 PROC_LOCK(p); 151 td->td_retval[0] = p->p_pgrp->pg_id; 152 PROC_UNLOCK(p); 153 return (0); 154 } 155 156 /* Get an arbitrary pid's process group id */ 157 #ifndef _SYS_SYSPROTO_H_ 158 struct getpgid_args { 159 pid_t pid; 160 }; 161 #endif 162 int 163 sys_getpgid(struct thread *td, struct getpgid_args *uap) 164 { 165 struct proc *p; 166 int error; 167 168 if (uap->pid == 0) { 169 p = td->td_proc; 170 PROC_LOCK(p); 171 } else { 172 p = pfind(uap->pid); 173 if (p == NULL) 174 return (ESRCH); 175 error = p_cansee(td, p); 176 if (error) { 177 PROC_UNLOCK(p); 178 return (error); 179 } 180 } 181 td->td_retval[0] = p->p_pgrp->pg_id; 182 PROC_UNLOCK(p); 183 return (0); 184 } 185 186 /* 187 * Get an arbitrary pid's session id. 188 */ 189 #ifndef _SYS_SYSPROTO_H_ 190 struct getsid_args { 191 pid_t pid; 192 }; 193 #endif 194 int 195 sys_getsid(struct thread *td, struct getsid_args *uap) 196 { 197 198 return (kern_getsid(td, uap->pid)); 199 } 200 201 int 202 kern_getsid(struct thread *td, pid_t pid) 203 { 204 struct proc *p; 205 int error; 206 207 if (pid == 0) { 208 p = td->td_proc; 209 PROC_LOCK(p); 210 } else { 211 p = pfind(pid); 212 if (p == NULL) 213 return (ESRCH); 214 error = p_cansee(td, p); 215 if (error) { 216 PROC_UNLOCK(p); 217 return (error); 218 } 219 } 220 td->td_retval[0] = p->p_session->s_sid; 221 PROC_UNLOCK(p); 222 return (0); 223 } 224 225 #ifndef _SYS_SYSPROTO_H_ 226 struct getuid_args { 227 int dummy; 228 }; 229 #endif 230 /* ARGSUSED */ 231 int 232 sys_getuid(struct thread *td, struct getuid_args *uap) 233 { 234 235 td->td_retval[0] = td->td_ucred->cr_ruid; 236 #if defined(COMPAT_43) 237 td->td_retval[1] = td->td_ucred->cr_uid; 238 #endif 239 return (0); 240 } 241 242 #ifndef _SYS_SYSPROTO_H_ 243 struct geteuid_args { 244 int dummy; 245 }; 246 #endif 247 /* ARGSUSED */ 248 int 249 sys_geteuid(struct thread *td, struct geteuid_args *uap) 250 { 251 252 td->td_retval[0] = td->td_ucred->cr_uid; 253 return (0); 254 } 255 256 #ifndef _SYS_SYSPROTO_H_ 257 struct getgid_args { 258 int dummy; 259 }; 260 #endif 261 /* ARGSUSED */ 262 int 263 sys_getgid(struct thread *td, struct getgid_args *uap) 264 { 265 266 td->td_retval[0] = td->td_ucred->cr_rgid; 267 #if defined(COMPAT_43) 268 td->td_retval[1] = td->td_ucred->cr_groups[0]; 269 #endif 270 return (0); 271 } 272 273 /* 274 * Get effective group ID. The "egid" is groups[0], and could be obtained 275 * via getgroups. This syscall exists because it is somewhat painful to do 276 * correctly in a library function. 277 */ 278 #ifndef _SYS_SYSPROTO_H_ 279 struct getegid_args { 280 int dummy; 281 }; 282 #endif 283 /* ARGSUSED */ 284 int 285 sys_getegid(struct thread *td, struct getegid_args *uap) 286 { 287 288 td->td_retval[0] = td->td_ucred->cr_groups[0]; 289 return (0); 290 } 291 292 #ifndef _SYS_SYSPROTO_H_ 293 struct getgroups_args { 294 int gidsetsize; 295 gid_t *gidset; 296 }; 297 #endif 298 int 299 sys_getgroups(struct thread *td, struct getgroups_args *uap) 300 { 301 struct ucred *cred; 302 int ngrp, error; 303 304 cred = td->td_ucred; 305 ngrp = cred->cr_ngroups; 306 307 if (uap->gidsetsize == 0) { 308 error = 0; 309 goto out; 310 } 311 if (uap->gidsetsize < ngrp) 312 return (EINVAL); 313 314 error = copyout(cred->cr_groups, uap->gidset, ngrp * sizeof(gid_t)); 315 out: 316 td->td_retval[0] = ngrp; 317 return (error); 318 } 319 320 #ifndef _SYS_SYSPROTO_H_ 321 struct setsid_args { 322 int dummy; 323 }; 324 #endif 325 /* ARGSUSED */ 326 int 327 sys_setsid(struct thread *td, struct setsid_args *uap) 328 { 329 struct pgrp *pgrp; 330 int error; 331 struct proc *p = td->td_proc; 332 struct pgrp *newpgrp; 333 struct session *newsess; 334 335 pgrp = NULL; 336 337 newpgrp = uma_zalloc(pgrp_zone, M_WAITOK); 338 newsess = malloc(sizeof(struct session), M_SESSION, M_WAITOK | M_ZERO); 339 340 again: 341 error = 0; 342 sx_xlock(&proctree_lock); 343 344 if (p->p_pgid == p->p_pid || (pgrp = pgfind(p->p_pid)) != NULL) { 345 if (pgrp != NULL) 346 PGRP_UNLOCK(pgrp); 347 error = EPERM; 348 } else { 349 error = enterpgrp(p, p->p_pid, newpgrp, newsess); 350 if (error == ERESTART) 351 goto again; 352 MPASS(error == 0); 353 td->td_retval[0] = p->p_pid; 354 newpgrp = NULL; 355 newsess = NULL; 356 } 357 358 sx_xunlock(&proctree_lock); 359 360 uma_zfree(pgrp_zone, newpgrp); 361 free(newsess, M_SESSION); 362 363 return (error); 364 } 365 366 /* 367 * set process group (setpgid/old setpgrp) 368 * 369 * caller does setpgid(targpid, targpgid) 370 * 371 * pid must be caller or child of caller (ESRCH) 372 * if a child 373 * pid must be in same session (EPERM) 374 * pid can't have done an exec (EACCES) 375 * if pgid != pid 376 * there must exist some pid in same session having pgid (EPERM) 377 * pid must not be session leader (EPERM) 378 */ 379 #ifndef _SYS_SYSPROTO_H_ 380 struct setpgid_args { 381 int pid; /* target process id */ 382 int pgid; /* target pgrp id */ 383 }; 384 #endif 385 /* ARGSUSED */ 386 int 387 sys_setpgid(struct thread *td, struct setpgid_args *uap) 388 { 389 struct proc *curp = td->td_proc; 390 struct proc *targp; /* target process */ 391 struct pgrp *pgrp; /* target pgrp */ 392 int error; 393 struct pgrp *newpgrp; 394 395 if (uap->pgid < 0) 396 return (EINVAL); 397 398 newpgrp = uma_zalloc(pgrp_zone, M_WAITOK); 399 400 again: 401 error = 0; 402 403 sx_xlock(&proctree_lock); 404 if (uap->pid != 0 && uap->pid != curp->p_pid) { 405 if ((targp = pfind(uap->pid)) == NULL) { 406 error = ESRCH; 407 goto done; 408 } 409 if (!inferior(targp)) { 410 PROC_UNLOCK(targp); 411 error = ESRCH; 412 goto done; 413 } 414 if ((error = p_cansee(td, targp))) { 415 PROC_UNLOCK(targp); 416 goto done; 417 } 418 if (targp->p_pgrp == NULL || 419 targp->p_session != curp->p_session) { 420 PROC_UNLOCK(targp); 421 error = EPERM; 422 goto done; 423 } 424 if (targp->p_flag & P_EXEC) { 425 PROC_UNLOCK(targp); 426 error = EACCES; 427 goto done; 428 } 429 PROC_UNLOCK(targp); 430 } else 431 targp = curp; 432 if (SESS_LEADER(targp)) { 433 error = EPERM; 434 goto done; 435 } 436 if (uap->pgid == 0) 437 uap->pgid = targp->p_pid; 438 if ((pgrp = pgfind(uap->pgid)) == NULL) { 439 if (uap->pgid == targp->p_pid) { 440 error = enterpgrp(targp, uap->pgid, newpgrp, 441 NULL); 442 if (error == 0) 443 newpgrp = NULL; 444 } else 445 error = EPERM; 446 } else { 447 if (pgrp == targp->p_pgrp) { 448 PGRP_UNLOCK(pgrp); 449 goto done; 450 } 451 if (pgrp->pg_id != targp->p_pid && 452 pgrp->pg_session != curp->p_session) { 453 PGRP_UNLOCK(pgrp); 454 error = EPERM; 455 goto done; 456 } 457 PGRP_UNLOCK(pgrp); 458 error = enterthispgrp(targp, pgrp); 459 } 460 done: 461 KASSERT(error == 0 || newpgrp != NULL, 462 ("setpgid failed and newpgrp is NULL")); 463 if (error == ERESTART) 464 goto again; 465 sx_xunlock(&proctree_lock); 466 uma_zfree(pgrp_zone, newpgrp); 467 return (error); 468 } 469 470 /* 471 * Use the clause in B.4.2.2 that allows setuid/setgid to be 4.2/4.3BSD 472 * compatible. It says that setting the uid/gid to euid/egid is a special 473 * case of "appropriate privilege". Once the rules are expanded out, this 474 * basically means that setuid(nnn) sets all three id's, in all permitted 475 * cases unless _POSIX_SAVED_IDS is enabled. In that case, setuid(getuid()) 476 * does not set the saved id - this is dangerous for traditional BSD 477 * programs. For this reason, we *really* do not want to set 478 * _POSIX_SAVED_IDS and do not want to clear POSIX_APPENDIX_B_4_2_2. 479 */ 480 #define POSIX_APPENDIX_B_4_2_2 481 482 #ifndef _SYS_SYSPROTO_H_ 483 struct setuid_args { 484 uid_t uid; 485 }; 486 #endif 487 /* ARGSUSED */ 488 int 489 sys_setuid(struct thread *td, struct setuid_args *uap) 490 { 491 struct proc *p = td->td_proc; 492 struct ucred *newcred, *oldcred; 493 uid_t uid; 494 struct uidinfo *uip; 495 int error; 496 497 uid = uap->uid; 498 AUDIT_ARG_UID(uid); 499 newcred = crget(); 500 uip = uifind(uid); 501 PROC_LOCK(p); 502 /* 503 * Copy credentials so other references do not see our changes. 504 */ 505 oldcred = crcopysafe(p, newcred); 506 507 #ifdef MAC 508 error = mac_cred_check_setuid(oldcred, uid); 509 if (error) 510 goto fail; 511 #endif 512 513 /* 514 * See if we have "permission" by POSIX 1003.1 rules. 515 * 516 * Note that setuid(geteuid()) is a special case of 517 * "appropriate privileges" in appendix B.4.2.2. We need 518 * to use this clause to be compatible with traditional BSD 519 * semantics. Basically, it means that "setuid(xx)" sets all 520 * three id's (assuming you have privs). 521 * 522 * Notes on the logic. We do things in three steps. 523 * 1: We determine if the euid is going to change, and do EPERM 524 * right away. We unconditionally change the euid later if this 525 * test is satisfied, simplifying that part of the logic. 526 * 2: We determine if the real and/or saved uids are going to 527 * change. Determined by compile options. 528 * 3: Change euid last. (after tests in #2 for "appropriate privs") 529 */ 530 if (uid != oldcred->cr_ruid && /* allow setuid(getuid()) */ 531 #ifdef _POSIX_SAVED_IDS 532 uid != oldcred->cr_svuid && /* allow setuid(saved gid) */ 533 #endif 534 #ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */ 535 uid != oldcred->cr_uid && /* allow setuid(geteuid()) */ 536 #endif 537 (error = priv_check_cred(oldcred, PRIV_CRED_SETUID)) != 0) 538 goto fail; 539 540 #ifdef _POSIX_SAVED_IDS 541 /* 542 * Do we have "appropriate privileges" (are we root or uid == euid) 543 * If so, we are changing the real uid and/or saved uid. 544 */ 545 if ( 546 #ifdef POSIX_APPENDIX_B_4_2_2 /* Use the clause from B.4.2.2 */ 547 uid == oldcred->cr_uid || 548 #endif 549 /* We are using privs. */ 550 priv_check_cred(oldcred, PRIV_CRED_SETUID) == 0) 551 #endif 552 { 553 /* 554 * Set the real uid and transfer proc count to new user. 555 */ 556 if (uid != oldcred->cr_ruid) { 557 change_ruid(newcred, uip); 558 setsugid(p); 559 } 560 /* 561 * Set saved uid 562 * 563 * XXX always set saved uid even if not _POSIX_SAVED_IDS, as 564 * the security of seteuid() depends on it. B.4.2.2 says it 565 * is important that we should do this. 566 */ 567 if (uid != oldcred->cr_svuid) { 568 change_svuid(newcred, uid); 569 setsugid(p); 570 } 571 } 572 573 /* 574 * In all permitted cases, we are changing the euid. 575 */ 576 if (uid != oldcred->cr_uid) { 577 change_euid(newcred, uip); 578 setsugid(p); 579 } 580 proc_set_cred(p, newcred); 581 #ifdef RACCT 582 racct_proc_ucred_changed(p, oldcred, newcred); 583 crhold(newcred); 584 #endif 585 PROC_UNLOCK(p); 586 #ifdef RCTL 587 rctl_proc_ucred_changed(p, newcred); 588 crfree(newcred); 589 #endif 590 uifree(uip); 591 crfree(oldcred); 592 return (0); 593 594 fail: 595 PROC_UNLOCK(p); 596 uifree(uip); 597 crfree(newcred); 598 return (error); 599 } 600 601 #ifndef _SYS_SYSPROTO_H_ 602 struct seteuid_args { 603 uid_t euid; 604 }; 605 #endif 606 /* ARGSUSED */ 607 int 608 sys_seteuid(struct thread *td, struct seteuid_args *uap) 609 { 610 struct proc *p = td->td_proc; 611 struct ucred *newcred, *oldcred; 612 uid_t euid; 613 struct uidinfo *euip; 614 int error; 615 616 euid = uap->euid; 617 AUDIT_ARG_EUID(euid); 618 newcred = crget(); 619 euip = uifind(euid); 620 PROC_LOCK(p); 621 /* 622 * Copy credentials so other references do not see our changes. 623 */ 624 oldcred = crcopysafe(p, newcred); 625 626 #ifdef MAC 627 error = mac_cred_check_seteuid(oldcred, euid); 628 if (error) 629 goto fail; 630 #endif 631 632 if (euid != oldcred->cr_ruid && /* allow seteuid(getuid()) */ 633 euid != oldcred->cr_svuid && /* allow seteuid(saved uid) */ 634 (error = priv_check_cred(oldcred, PRIV_CRED_SETEUID)) != 0) 635 goto fail; 636 637 /* 638 * Everything's okay, do it. 639 */ 640 if (oldcred->cr_uid != euid) { 641 change_euid(newcred, euip); 642 setsugid(p); 643 } 644 proc_set_cred(p, newcred); 645 PROC_UNLOCK(p); 646 uifree(euip); 647 crfree(oldcred); 648 return (0); 649 650 fail: 651 PROC_UNLOCK(p); 652 uifree(euip); 653 crfree(newcred); 654 return (error); 655 } 656 657 #ifndef _SYS_SYSPROTO_H_ 658 struct setgid_args { 659 gid_t gid; 660 }; 661 #endif 662 /* ARGSUSED */ 663 int 664 sys_setgid(struct thread *td, struct setgid_args *uap) 665 { 666 struct proc *p = td->td_proc; 667 struct ucred *newcred, *oldcred; 668 gid_t gid; 669 int error; 670 671 gid = uap->gid; 672 AUDIT_ARG_GID(gid); 673 newcred = crget(); 674 PROC_LOCK(p); 675 oldcred = crcopysafe(p, newcred); 676 677 #ifdef MAC 678 error = mac_cred_check_setgid(oldcred, gid); 679 if (error) 680 goto fail; 681 #endif 682 683 /* 684 * See if we have "permission" by POSIX 1003.1 rules. 685 * 686 * Note that setgid(getegid()) is a special case of 687 * "appropriate privileges" in appendix B.4.2.2. We need 688 * to use this clause to be compatible with traditional BSD 689 * semantics. Basically, it means that "setgid(xx)" sets all 690 * three id's (assuming you have privs). 691 * 692 * For notes on the logic here, see setuid() above. 693 */ 694 if (gid != oldcred->cr_rgid && /* allow setgid(getgid()) */ 695 #ifdef _POSIX_SAVED_IDS 696 gid != oldcred->cr_svgid && /* allow setgid(saved gid) */ 697 #endif 698 #ifdef POSIX_APPENDIX_B_4_2_2 /* Use BSD-compat clause from B.4.2.2 */ 699 gid != oldcred->cr_groups[0] && /* allow setgid(getegid()) */ 700 #endif 701 (error = priv_check_cred(oldcred, PRIV_CRED_SETGID)) != 0) 702 goto fail; 703 704 #ifdef _POSIX_SAVED_IDS 705 /* 706 * Do we have "appropriate privileges" (are we root or gid == egid) 707 * If so, we are changing the real uid and saved gid. 708 */ 709 if ( 710 #ifdef POSIX_APPENDIX_B_4_2_2 /* use the clause from B.4.2.2 */ 711 gid == oldcred->cr_groups[0] || 712 #endif 713 /* We are using privs. */ 714 priv_check_cred(oldcred, PRIV_CRED_SETGID) == 0) 715 #endif 716 { 717 /* 718 * Set real gid 719 */ 720 if (oldcred->cr_rgid != gid) { 721 change_rgid(newcred, gid); 722 setsugid(p); 723 } 724 /* 725 * Set saved gid 726 * 727 * XXX always set saved gid even if not _POSIX_SAVED_IDS, as 728 * the security of setegid() depends on it. B.4.2.2 says it 729 * is important that we should do this. 730 */ 731 if (oldcred->cr_svgid != gid) { 732 change_svgid(newcred, gid); 733 setsugid(p); 734 } 735 } 736 /* 737 * In all cases permitted cases, we are changing the egid. 738 * Copy credentials so other references do not see our changes. 739 */ 740 if (oldcred->cr_groups[0] != gid) { 741 change_egid(newcred, gid); 742 setsugid(p); 743 } 744 proc_set_cred(p, newcred); 745 PROC_UNLOCK(p); 746 crfree(oldcred); 747 return (0); 748 749 fail: 750 PROC_UNLOCK(p); 751 crfree(newcred); 752 return (error); 753 } 754 755 #ifndef _SYS_SYSPROTO_H_ 756 struct setegid_args { 757 gid_t egid; 758 }; 759 #endif 760 /* ARGSUSED */ 761 int 762 sys_setegid(struct thread *td, struct setegid_args *uap) 763 { 764 struct proc *p = td->td_proc; 765 struct ucred *newcred, *oldcred; 766 gid_t egid; 767 int error; 768 769 egid = uap->egid; 770 AUDIT_ARG_EGID(egid); 771 newcred = crget(); 772 PROC_LOCK(p); 773 oldcred = crcopysafe(p, newcred); 774 775 #ifdef MAC 776 error = mac_cred_check_setegid(oldcred, egid); 777 if (error) 778 goto fail; 779 #endif 780 781 if (egid != oldcred->cr_rgid && /* allow setegid(getgid()) */ 782 egid != oldcred->cr_svgid && /* allow setegid(saved gid) */ 783 (error = priv_check_cred(oldcred, PRIV_CRED_SETEGID)) != 0) 784 goto fail; 785 786 if (oldcred->cr_groups[0] != egid) { 787 change_egid(newcred, egid); 788 setsugid(p); 789 } 790 proc_set_cred(p, newcred); 791 PROC_UNLOCK(p); 792 crfree(oldcred); 793 return (0); 794 795 fail: 796 PROC_UNLOCK(p); 797 crfree(newcred); 798 return (error); 799 } 800 801 #ifndef _SYS_SYSPROTO_H_ 802 struct setgroups_args { 803 int gidsetsize; 804 gid_t *gidset; 805 }; 806 #endif 807 /* ARGSUSED */ 808 int 809 sys_setgroups(struct thread *td, struct setgroups_args *uap) 810 { 811 gid_t smallgroups[XU_NGROUPS]; 812 gid_t *groups; 813 int gidsetsize, error; 814 815 gidsetsize = uap->gidsetsize; 816 if (gidsetsize > ngroups_max + 1 || gidsetsize < 0) 817 return (EINVAL); 818 819 if (gidsetsize > XU_NGROUPS) 820 groups = malloc(gidsetsize * sizeof(gid_t), M_TEMP, M_WAITOK); 821 else 822 groups = smallgroups; 823 824 error = copyin(uap->gidset, groups, gidsetsize * sizeof(gid_t)); 825 if (error == 0) 826 error = kern_setgroups(td, gidsetsize, groups); 827 828 if (gidsetsize > XU_NGROUPS) 829 free(groups, M_TEMP); 830 return (error); 831 } 832 833 int 834 kern_setgroups(struct thread *td, u_int ngrp, gid_t *groups) 835 { 836 struct proc *p = td->td_proc; 837 struct ucred *newcred, *oldcred; 838 int error; 839 840 MPASS(ngrp <= ngroups_max + 1); 841 AUDIT_ARG_GROUPSET(groups, ngrp); 842 newcred = crget(); 843 crextend(newcred, ngrp); 844 PROC_LOCK(p); 845 oldcred = crcopysafe(p, newcred); 846 847 #ifdef MAC 848 error = mac_cred_check_setgroups(oldcred, ngrp, groups); 849 if (error) 850 goto fail; 851 #endif 852 853 error = priv_check_cred(oldcred, PRIV_CRED_SETGROUPS); 854 if (error) 855 goto fail; 856 857 if (ngrp == 0) { 858 /* 859 * setgroups(0, NULL) is a legitimate way of clearing the 860 * groups vector on non-BSD systems (which generally do not 861 * have the egid in the groups[0]). We risk security holes 862 * when running non-BSD software if we do not do the same. 863 */ 864 newcred->cr_ngroups = 1; 865 } else { 866 crsetgroups_locked(newcred, ngrp, groups); 867 } 868 setsugid(p); 869 proc_set_cred(p, newcred); 870 PROC_UNLOCK(p); 871 crfree(oldcred); 872 return (0); 873 874 fail: 875 PROC_UNLOCK(p); 876 crfree(newcred); 877 return (error); 878 } 879 880 #ifndef _SYS_SYSPROTO_H_ 881 struct setreuid_args { 882 uid_t ruid; 883 uid_t euid; 884 }; 885 #endif 886 /* ARGSUSED */ 887 int 888 sys_setreuid(struct thread *td, struct setreuid_args *uap) 889 { 890 struct proc *p = td->td_proc; 891 struct ucred *newcred, *oldcred; 892 uid_t euid, ruid; 893 struct uidinfo *euip, *ruip; 894 int error; 895 896 euid = uap->euid; 897 ruid = uap->ruid; 898 AUDIT_ARG_EUID(euid); 899 AUDIT_ARG_RUID(ruid); 900 newcred = crget(); 901 euip = uifind(euid); 902 ruip = uifind(ruid); 903 PROC_LOCK(p); 904 oldcred = crcopysafe(p, newcred); 905 906 #ifdef MAC 907 error = mac_cred_check_setreuid(oldcred, ruid, euid); 908 if (error) 909 goto fail; 910 #endif 911 912 if (((ruid != (uid_t)-1 && ruid != oldcred->cr_ruid && 913 ruid != oldcred->cr_svuid) || 914 (euid != (uid_t)-1 && euid != oldcred->cr_uid && 915 euid != oldcred->cr_ruid && euid != oldcred->cr_svuid)) && 916 (error = priv_check_cred(oldcred, PRIV_CRED_SETREUID)) != 0) 917 goto fail; 918 919 if (euid != (uid_t)-1 && oldcred->cr_uid != euid) { 920 change_euid(newcred, euip); 921 setsugid(p); 922 } 923 if (ruid != (uid_t)-1 && oldcred->cr_ruid != ruid) { 924 change_ruid(newcred, ruip); 925 setsugid(p); 926 } 927 if ((ruid != (uid_t)-1 || newcred->cr_uid != newcred->cr_ruid) && 928 newcred->cr_svuid != newcred->cr_uid) { 929 change_svuid(newcred, newcred->cr_uid); 930 setsugid(p); 931 } 932 proc_set_cred(p, newcred); 933 #ifdef RACCT 934 racct_proc_ucred_changed(p, oldcred, newcred); 935 crhold(newcred); 936 #endif 937 PROC_UNLOCK(p); 938 #ifdef RCTL 939 rctl_proc_ucred_changed(p, newcred); 940 crfree(newcred); 941 #endif 942 uifree(ruip); 943 uifree(euip); 944 crfree(oldcred); 945 return (0); 946 947 fail: 948 PROC_UNLOCK(p); 949 uifree(ruip); 950 uifree(euip); 951 crfree(newcred); 952 return (error); 953 } 954 955 #ifndef _SYS_SYSPROTO_H_ 956 struct setregid_args { 957 gid_t rgid; 958 gid_t egid; 959 }; 960 #endif 961 /* ARGSUSED */ 962 int 963 sys_setregid(struct thread *td, struct setregid_args *uap) 964 { 965 struct proc *p = td->td_proc; 966 struct ucred *newcred, *oldcred; 967 gid_t egid, rgid; 968 int error; 969 970 egid = uap->egid; 971 rgid = uap->rgid; 972 AUDIT_ARG_EGID(egid); 973 AUDIT_ARG_RGID(rgid); 974 newcred = crget(); 975 PROC_LOCK(p); 976 oldcred = crcopysafe(p, newcred); 977 978 #ifdef MAC 979 error = mac_cred_check_setregid(oldcred, rgid, egid); 980 if (error) 981 goto fail; 982 #endif 983 984 if (((rgid != (gid_t)-1 && rgid != oldcred->cr_rgid && 985 rgid != oldcred->cr_svgid) || 986 (egid != (gid_t)-1 && egid != oldcred->cr_groups[0] && 987 egid != oldcred->cr_rgid && egid != oldcred->cr_svgid)) && 988 (error = priv_check_cred(oldcred, PRIV_CRED_SETREGID)) != 0) 989 goto fail; 990 991 if (egid != (gid_t)-1 && oldcred->cr_groups[0] != egid) { 992 change_egid(newcred, egid); 993 setsugid(p); 994 } 995 if (rgid != (gid_t)-1 && oldcred->cr_rgid != rgid) { 996 change_rgid(newcred, rgid); 997 setsugid(p); 998 } 999 if ((rgid != (gid_t)-1 || newcred->cr_groups[0] != newcred->cr_rgid) && 1000 newcred->cr_svgid != newcred->cr_groups[0]) { 1001 change_svgid(newcred, newcred->cr_groups[0]); 1002 setsugid(p); 1003 } 1004 proc_set_cred(p, newcred); 1005 PROC_UNLOCK(p); 1006 crfree(oldcred); 1007 return (0); 1008 1009 fail: 1010 PROC_UNLOCK(p); 1011 crfree(newcred); 1012 return (error); 1013 } 1014 1015 /* 1016 * setresuid(ruid, euid, suid) is like setreuid except control over the saved 1017 * uid is explicit. 1018 */ 1019 #ifndef _SYS_SYSPROTO_H_ 1020 struct setresuid_args { 1021 uid_t ruid; 1022 uid_t euid; 1023 uid_t suid; 1024 }; 1025 #endif 1026 /* ARGSUSED */ 1027 int 1028 sys_setresuid(struct thread *td, struct setresuid_args *uap) 1029 { 1030 struct proc *p = td->td_proc; 1031 struct ucred *newcred, *oldcred; 1032 uid_t euid, ruid, suid; 1033 struct uidinfo *euip, *ruip; 1034 int error; 1035 1036 euid = uap->euid; 1037 ruid = uap->ruid; 1038 suid = uap->suid; 1039 AUDIT_ARG_EUID(euid); 1040 AUDIT_ARG_RUID(ruid); 1041 AUDIT_ARG_SUID(suid); 1042 newcred = crget(); 1043 euip = uifind(euid); 1044 ruip = uifind(ruid); 1045 PROC_LOCK(p); 1046 oldcred = crcopysafe(p, newcred); 1047 1048 #ifdef MAC 1049 error = mac_cred_check_setresuid(oldcred, ruid, euid, suid); 1050 if (error) 1051 goto fail; 1052 #endif 1053 1054 if (((ruid != (uid_t)-1 && ruid != oldcred->cr_ruid && 1055 ruid != oldcred->cr_svuid && 1056 ruid != oldcred->cr_uid) || 1057 (euid != (uid_t)-1 && euid != oldcred->cr_ruid && 1058 euid != oldcred->cr_svuid && 1059 euid != oldcred->cr_uid) || 1060 (suid != (uid_t)-1 && suid != oldcred->cr_ruid && 1061 suid != oldcred->cr_svuid && 1062 suid != oldcred->cr_uid)) && 1063 (error = priv_check_cred(oldcred, PRIV_CRED_SETRESUID)) != 0) 1064 goto fail; 1065 1066 if (euid != (uid_t)-1 && oldcred->cr_uid != euid) { 1067 change_euid(newcred, euip); 1068 setsugid(p); 1069 } 1070 if (ruid != (uid_t)-1 && oldcred->cr_ruid != ruid) { 1071 change_ruid(newcred, ruip); 1072 setsugid(p); 1073 } 1074 if (suid != (uid_t)-1 && oldcred->cr_svuid != suid) { 1075 change_svuid(newcred, suid); 1076 setsugid(p); 1077 } 1078 proc_set_cred(p, newcred); 1079 #ifdef RACCT 1080 racct_proc_ucred_changed(p, oldcred, newcred); 1081 crhold(newcred); 1082 #endif 1083 PROC_UNLOCK(p); 1084 #ifdef RCTL 1085 rctl_proc_ucred_changed(p, newcred); 1086 crfree(newcred); 1087 #endif 1088 uifree(ruip); 1089 uifree(euip); 1090 crfree(oldcred); 1091 return (0); 1092 1093 fail: 1094 PROC_UNLOCK(p); 1095 uifree(ruip); 1096 uifree(euip); 1097 crfree(newcred); 1098 return (error); 1099 1100 } 1101 1102 /* 1103 * setresgid(rgid, egid, sgid) is like setregid except control over the saved 1104 * gid is explicit. 1105 */ 1106 #ifndef _SYS_SYSPROTO_H_ 1107 struct setresgid_args { 1108 gid_t rgid; 1109 gid_t egid; 1110 gid_t sgid; 1111 }; 1112 #endif 1113 /* ARGSUSED */ 1114 int 1115 sys_setresgid(struct thread *td, struct setresgid_args *uap) 1116 { 1117 struct proc *p = td->td_proc; 1118 struct ucred *newcred, *oldcred; 1119 gid_t egid, rgid, sgid; 1120 int error; 1121 1122 egid = uap->egid; 1123 rgid = uap->rgid; 1124 sgid = uap->sgid; 1125 AUDIT_ARG_EGID(egid); 1126 AUDIT_ARG_RGID(rgid); 1127 AUDIT_ARG_SGID(sgid); 1128 newcred = crget(); 1129 PROC_LOCK(p); 1130 oldcred = crcopysafe(p, newcred); 1131 1132 #ifdef MAC 1133 error = mac_cred_check_setresgid(oldcred, rgid, egid, sgid); 1134 if (error) 1135 goto fail; 1136 #endif 1137 1138 if (((rgid != (gid_t)-1 && rgid != oldcred->cr_rgid && 1139 rgid != oldcred->cr_svgid && 1140 rgid != oldcred->cr_groups[0]) || 1141 (egid != (gid_t)-1 && egid != oldcred->cr_rgid && 1142 egid != oldcred->cr_svgid && 1143 egid != oldcred->cr_groups[0]) || 1144 (sgid != (gid_t)-1 && sgid != oldcred->cr_rgid && 1145 sgid != oldcred->cr_svgid && 1146 sgid != oldcred->cr_groups[0])) && 1147 (error = priv_check_cred(oldcred, PRIV_CRED_SETRESGID)) != 0) 1148 goto fail; 1149 1150 if (egid != (gid_t)-1 && oldcred->cr_groups[0] != egid) { 1151 change_egid(newcred, egid); 1152 setsugid(p); 1153 } 1154 if (rgid != (gid_t)-1 && oldcred->cr_rgid != rgid) { 1155 change_rgid(newcred, rgid); 1156 setsugid(p); 1157 } 1158 if (sgid != (gid_t)-1 && oldcred->cr_svgid != sgid) { 1159 change_svgid(newcred, sgid); 1160 setsugid(p); 1161 } 1162 proc_set_cred(p, newcred); 1163 PROC_UNLOCK(p); 1164 crfree(oldcred); 1165 return (0); 1166 1167 fail: 1168 PROC_UNLOCK(p); 1169 crfree(newcred); 1170 return (error); 1171 } 1172 1173 #ifndef _SYS_SYSPROTO_H_ 1174 struct getresuid_args { 1175 uid_t *ruid; 1176 uid_t *euid; 1177 uid_t *suid; 1178 }; 1179 #endif 1180 /* ARGSUSED */ 1181 int 1182 sys_getresuid(struct thread *td, struct getresuid_args *uap) 1183 { 1184 struct ucred *cred; 1185 int error1 = 0, error2 = 0, error3 = 0; 1186 1187 cred = td->td_ucred; 1188 if (uap->ruid) 1189 error1 = copyout(&cred->cr_ruid, 1190 uap->ruid, sizeof(cred->cr_ruid)); 1191 if (uap->euid) 1192 error2 = copyout(&cred->cr_uid, 1193 uap->euid, sizeof(cred->cr_uid)); 1194 if (uap->suid) 1195 error3 = copyout(&cred->cr_svuid, 1196 uap->suid, sizeof(cred->cr_svuid)); 1197 return (error1 ? error1 : error2 ? error2 : error3); 1198 } 1199 1200 #ifndef _SYS_SYSPROTO_H_ 1201 struct getresgid_args { 1202 gid_t *rgid; 1203 gid_t *egid; 1204 gid_t *sgid; 1205 }; 1206 #endif 1207 /* ARGSUSED */ 1208 int 1209 sys_getresgid(struct thread *td, struct getresgid_args *uap) 1210 { 1211 struct ucred *cred; 1212 int error1 = 0, error2 = 0, error3 = 0; 1213 1214 cred = td->td_ucred; 1215 if (uap->rgid) 1216 error1 = copyout(&cred->cr_rgid, 1217 uap->rgid, sizeof(cred->cr_rgid)); 1218 if (uap->egid) 1219 error2 = copyout(&cred->cr_groups[0], 1220 uap->egid, sizeof(cred->cr_groups[0])); 1221 if (uap->sgid) 1222 error3 = copyout(&cred->cr_svgid, 1223 uap->sgid, sizeof(cred->cr_svgid)); 1224 return (error1 ? error1 : error2 ? error2 : error3); 1225 } 1226 1227 #ifndef _SYS_SYSPROTO_H_ 1228 struct issetugid_args { 1229 int dummy; 1230 }; 1231 #endif 1232 /* ARGSUSED */ 1233 int 1234 sys_issetugid(struct thread *td, struct issetugid_args *uap) 1235 { 1236 struct proc *p = td->td_proc; 1237 1238 /* 1239 * Note: OpenBSD sets a P_SUGIDEXEC flag set at execve() time, 1240 * we use P_SUGID because we consider changing the owners as 1241 * "tainting" as well. 1242 * This is significant for procs that start as root and "become" 1243 * a user without an exec - programs cannot know *everything* 1244 * that libc *might* have put in their data segment. 1245 */ 1246 td->td_retval[0] = (p->p_flag & P_SUGID) ? 1 : 0; 1247 return (0); 1248 } 1249 1250 int 1251 sys___setugid(struct thread *td, struct __setugid_args *uap) 1252 { 1253 #ifdef REGRESSION 1254 struct proc *p; 1255 1256 p = td->td_proc; 1257 switch (uap->flag) { 1258 case 0: 1259 PROC_LOCK(p); 1260 p->p_flag &= ~P_SUGID; 1261 PROC_UNLOCK(p); 1262 return (0); 1263 case 1: 1264 PROC_LOCK(p); 1265 p->p_flag |= P_SUGID; 1266 PROC_UNLOCK(p); 1267 return (0); 1268 default: 1269 return (EINVAL); 1270 } 1271 #else /* !REGRESSION */ 1272 1273 return (ENOSYS); 1274 #endif /* REGRESSION */ 1275 } 1276 1277 /* 1278 * Returns whether gid designates a supplementary group in cred. 1279 */ 1280 static bool 1281 supplementary_group_member(gid_t gid, struct ucred *cred) 1282 { 1283 int l, h, m; 1284 1285 /* 1286 * Perform a binary search of the supplemental groups. This is possible 1287 * because we sort the groups in crsetgroups(). 1288 */ 1289 l = 1; 1290 h = cred->cr_ngroups; 1291 1292 while (l < h) { 1293 m = l + (h - l) / 2; 1294 if (cred->cr_groups[m] < gid) 1295 l = m + 1; 1296 else 1297 h = m; 1298 } 1299 1300 return (l < cred->cr_ngroups && cred->cr_groups[l] == gid); 1301 } 1302 1303 /* 1304 * Check if gid is a member of the (effective) group set (i.e., effective and 1305 * supplementary groups). 1306 */ 1307 bool 1308 groupmember(gid_t gid, struct ucred *cred) 1309 { 1310 1311 if (gid == cred->cr_groups[0]) 1312 return (true); 1313 1314 return (supplementary_group_member(gid, cred)); 1315 } 1316 1317 /* 1318 * Check if gid is a member of the real group set (i.e., real and supplementary 1319 * groups). 1320 */ 1321 bool 1322 realgroupmember(gid_t gid, struct ucred *cred) 1323 { 1324 if (gid == cred->cr_rgid) 1325 return (true); 1326 1327 return (supplementary_group_member(gid, cred)); 1328 } 1329 1330 /* 1331 * Test the active securelevel against a given level. securelevel_gt() 1332 * implements (securelevel > level). securelevel_ge() implements 1333 * (securelevel >= level). Note that the logic is inverted -- these 1334 * functions return EPERM on "success" and 0 on "failure". 1335 * 1336 * Due to care taken when setting the securelevel, we know that no jail will 1337 * be less secure that its parent (or the physical system), so it is sufficient 1338 * to test the current jail only. 1339 * 1340 * XXXRW: Possibly since this has to do with privilege, it should move to 1341 * kern_priv.c. 1342 */ 1343 int 1344 securelevel_gt(struct ucred *cr, int level) 1345 { 1346 1347 return (cr->cr_prison->pr_securelevel > level ? EPERM : 0); 1348 } 1349 1350 int 1351 securelevel_ge(struct ucred *cr, int level) 1352 { 1353 1354 return (cr->cr_prison->pr_securelevel >= level ? EPERM : 0); 1355 } 1356 1357 /* 1358 * 'see_other_uids' determines whether or not visibility of processes 1359 * and sockets with credentials holding different real uids is possible 1360 * using a variety of system MIBs. 1361 * XXX: data declarations should be together near the beginning of the file. 1362 */ 1363 static int see_other_uids = 1; 1364 SYSCTL_INT(_security_bsd, OID_AUTO, see_other_uids, CTLFLAG_RW, 1365 &see_other_uids, 0, 1366 "Unprivileged processes may see subjects/objects with different real uid"); 1367 1368 /*- 1369 * Determine if u1 "can see" the subject specified by u2, according to the 1370 * 'see_other_uids' policy. 1371 * Returns: 0 for permitted, ESRCH otherwise 1372 * Locks: none 1373 * References: *u1 and *u2 must not change during the call 1374 * u1 may equal u2, in which case only one reference is required 1375 */ 1376 static int 1377 cr_canseeotheruids(struct ucred *u1, struct ucred *u2) 1378 { 1379 1380 if (!see_other_uids && u1->cr_ruid != u2->cr_ruid) { 1381 if (priv_check_cred(u1, PRIV_SEEOTHERUIDS) != 0) 1382 return (ESRCH); 1383 } 1384 return (0); 1385 } 1386 1387 /* 1388 * 'see_other_gids' determines whether or not visibility of processes 1389 * and sockets with credentials holding different real gids is possible 1390 * using a variety of system MIBs. 1391 * XXX: data declarations should be together near the beginning of the file. 1392 */ 1393 static int see_other_gids = 1; 1394 SYSCTL_INT(_security_bsd, OID_AUTO, see_other_gids, CTLFLAG_RW, 1395 &see_other_gids, 0, 1396 "Unprivileged processes may see subjects/objects with different real gid"); 1397 1398 /* 1399 * Determine if u1 can "see" the subject specified by u2, according to the 1400 * 'see_other_gids' policy. 1401 * Returns: 0 for permitted, ESRCH otherwise 1402 * Locks: none 1403 * References: *u1 and *u2 must not change during the call 1404 * u1 may equal u2, in which case only one reference is required 1405 */ 1406 static int 1407 cr_canseeothergids(struct ucred *u1, struct ucred *u2) 1408 { 1409 if (!see_other_gids) { 1410 if (realgroupmember(u1->cr_rgid, u2)) 1411 return (0); 1412 1413 for (int i = 1; i < u1->cr_ngroups; i++) 1414 if (realgroupmember(u1->cr_groups[i], u2)) 1415 return (0); 1416 1417 if (priv_check_cred(u1, PRIV_SEEOTHERGIDS) != 0) 1418 return (ESRCH); 1419 } 1420 1421 return (0); 1422 } 1423 1424 /* 1425 * 'see_jail_proc' determines whether or not visibility of processes and 1426 * sockets with credentials holding different jail ids is possible using a 1427 * variety of system MIBs. 1428 * 1429 * XXX: data declarations should be together near the beginning of the file. 1430 */ 1431 1432 static int see_jail_proc = 1; 1433 SYSCTL_INT(_security_bsd, OID_AUTO, see_jail_proc, CTLFLAG_RW, 1434 &see_jail_proc, 0, 1435 "Unprivileged processes may see subjects/objects with different jail ids"); 1436 1437 /*- 1438 * Determine if u1 "can see" the subject specified by u2, according to the 1439 * 'see_jail_proc' policy. 1440 * Returns: 0 for permitted, ESRCH otherwise 1441 * Locks: none 1442 * References: *u1 and *u2 must not change during the call 1443 * u1 may equal u2, in which case only one reference is required 1444 */ 1445 static int 1446 cr_canseejailproc(struct ucred *u1, struct ucred *u2) 1447 { 1448 if (see_jail_proc || /* Policy deactivated. */ 1449 u1->cr_prison == u2->cr_prison || /* Same jail. */ 1450 priv_check_cred(u1, PRIV_SEEJAILPROC) == 0) /* Privileged. */ 1451 return (0); 1452 1453 return (ESRCH); 1454 } 1455 1456 /* 1457 * Helper for cr_cansee*() functions to abide by system-wide security.bsd.see_* 1458 * policies. Determines if u1 "can see" u2 according to these policies. 1459 * Returns: 0 for permitted, ESRCH otherwise 1460 */ 1461 int 1462 cr_bsd_visible(struct ucred *u1, struct ucred *u2) 1463 { 1464 int error; 1465 1466 if ((error = cr_canseeotheruids(u1, u2))) 1467 return (error); 1468 if ((error = cr_canseeothergids(u1, u2))) 1469 return (error); 1470 if ((error = cr_canseejailproc(u1, u2))) 1471 return (error); 1472 return (0); 1473 } 1474 1475 /*- 1476 * Determine if u1 "can see" the subject specified by u2. 1477 * Returns: 0 for permitted, an errno value otherwise 1478 * Locks: none 1479 * References: *u1 and *u2 must not change during the call 1480 * u1 may equal u2, in which case only one reference is required 1481 */ 1482 int 1483 cr_cansee(struct ucred *u1, struct ucred *u2) 1484 { 1485 int error; 1486 1487 if ((error = prison_check(u1, u2))) 1488 return (error); 1489 #ifdef MAC 1490 if ((error = mac_cred_check_visible(u1, u2))) 1491 return (error); 1492 #endif 1493 if ((error = cr_bsd_visible(u1, u2))) 1494 return (error); 1495 return (0); 1496 } 1497 1498 /*- 1499 * Determine if td "can see" the subject specified by p. 1500 * Returns: 0 for permitted, an errno value otherwise 1501 * Locks: Sufficient locks to protect p->p_ucred must be held. td really 1502 * should be curthread. 1503 * References: td and p must be valid for the lifetime of the call 1504 */ 1505 int 1506 p_cansee(struct thread *td, struct proc *p) 1507 { 1508 /* Wrap cr_cansee() for all functionality. */ 1509 KASSERT(td == curthread, ("%s: td not curthread", __func__)); 1510 PROC_LOCK_ASSERT(p, MA_OWNED); 1511 1512 if (td->td_proc == p) 1513 return (0); 1514 return (cr_cansee(td->td_ucred, p->p_ucred)); 1515 } 1516 1517 /* 1518 * 'conservative_signals' prevents the delivery of a broad class of 1519 * signals by unprivileged processes to processes that have changed their 1520 * credentials since the last invocation of execve(). This can prevent 1521 * the leakage of cached information or retained privileges as a result 1522 * of a common class of signal-related vulnerabilities. However, this 1523 * may interfere with some applications that expect to be able to 1524 * deliver these signals to peer processes after having given up 1525 * privilege. 1526 */ 1527 static int conservative_signals = 1; 1528 SYSCTL_INT(_security_bsd, OID_AUTO, conservative_signals, CTLFLAG_RW, 1529 &conservative_signals, 0, "Unprivileged processes prevented from " 1530 "sending certain signals to processes whose credentials have changed"); 1531 /*- 1532 * Determine whether cred may deliver the specified signal to proc. 1533 * Returns: 0 for permitted, an errno value otherwise. 1534 * Locks: A lock must be held for proc. 1535 * References: cred and proc must be valid for the lifetime of the call. 1536 */ 1537 int 1538 cr_cansignal(struct ucred *cred, struct proc *proc, int signum) 1539 { 1540 int error; 1541 1542 PROC_LOCK_ASSERT(proc, MA_OWNED); 1543 /* 1544 * Jail semantics limit the scope of signalling to proc in the 1545 * same jail as cred, if cred is in jail. 1546 */ 1547 error = prison_check(cred, proc->p_ucred); 1548 if (error) 1549 return (error); 1550 #ifdef MAC 1551 if ((error = mac_proc_check_signal(cred, proc, signum))) 1552 return (error); 1553 #endif 1554 if ((error = cr_bsd_visible(cred, proc->p_ucred))) 1555 return (error); 1556 1557 /* 1558 * UNIX signal semantics depend on the status of the P_SUGID 1559 * bit on the target process. If the bit is set, then additional 1560 * restrictions are placed on the set of available signals. 1561 */ 1562 if (conservative_signals && (proc->p_flag & P_SUGID)) { 1563 switch (signum) { 1564 case 0: 1565 case SIGKILL: 1566 case SIGINT: 1567 case SIGTERM: 1568 case SIGALRM: 1569 case SIGSTOP: 1570 case SIGTTIN: 1571 case SIGTTOU: 1572 case SIGTSTP: 1573 case SIGHUP: 1574 case SIGUSR1: 1575 case SIGUSR2: 1576 /* 1577 * Generally, permit job and terminal control 1578 * signals. 1579 */ 1580 break; 1581 default: 1582 /* Not permitted without privilege. */ 1583 error = priv_check_cred(cred, PRIV_SIGNAL_SUGID); 1584 if (error) 1585 return (error); 1586 } 1587 } 1588 1589 /* 1590 * Generally, the target credential's ruid or svuid must match the 1591 * subject credential's ruid or euid. 1592 */ 1593 if (cred->cr_ruid != proc->p_ucred->cr_ruid && 1594 cred->cr_ruid != proc->p_ucred->cr_svuid && 1595 cred->cr_uid != proc->p_ucred->cr_ruid && 1596 cred->cr_uid != proc->p_ucred->cr_svuid) { 1597 error = priv_check_cred(cred, PRIV_SIGNAL_DIFFCRED); 1598 if (error) 1599 return (error); 1600 } 1601 1602 return (0); 1603 } 1604 1605 /*- 1606 * Determine whether td may deliver the specified signal to p. 1607 * Returns: 0 for permitted, an errno value otherwise 1608 * Locks: Sufficient locks to protect various components of td and p 1609 * must be held. td must be curthread, and a lock must be 1610 * held for p. 1611 * References: td and p must be valid for the lifetime of the call 1612 */ 1613 int 1614 p_cansignal(struct thread *td, struct proc *p, int signum) 1615 { 1616 1617 KASSERT(td == curthread, ("%s: td not curthread", __func__)); 1618 PROC_LOCK_ASSERT(p, MA_OWNED); 1619 if (td->td_proc == p) 1620 return (0); 1621 1622 /* 1623 * UNIX signalling semantics require that processes in the same 1624 * session always be able to deliver SIGCONT to one another, 1625 * overriding the remaining protections. 1626 */ 1627 /* XXX: This will require an additional lock of some sort. */ 1628 if (signum == SIGCONT && td->td_proc->p_session == p->p_session) 1629 return (0); 1630 /* 1631 * Some compat layers use SIGTHR and higher signals for 1632 * communication between different kernel threads of the same 1633 * process, so that they expect that it's always possible to 1634 * deliver them, even for suid applications where cr_cansignal() can 1635 * deny such ability for security consideration. It should be 1636 * pretty safe to do since the only way to create two processes 1637 * with the same p_leader is via rfork(2). 1638 */ 1639 if (td->td_proc->p_leader != NULL && signum >= SIGTHR && 1640 signum < SIGTHR + 4 && td->td_proc->p_leader == p->p_leader) 1641 return (0); 1642 1643 return (cr_cansignal(td->td_ucred, p, signum)); 1644 } 1645 1646 /*- 1647 * Determine whether td may reschedule p. 1648 * Returns: 0 for permitted, an errno value otherwise 1649 * Locks: Sufficient locks to protect various components of td and p 1650 * must be held. td must be curthread, and a lock must 1651 * be held for p. 1652 * References: td and p must be valid for the lifetime of the call 1653 */ 1654 int 1655 p_cansched(struct thread *td, struct proc *p) 1656 { 1657 int error; 1658 1659 KASSERT(td == curthread, ("%s: td not curthread", __func__)); 1660 PROC_LOCK_ASSERT(p, MA_OWNED); 1661 if (td->td_proc == p) 1662 return (0); 1663 if ((error = prison_check(td->td_ucred, p->p_ucred))) 1664 return (error); 1665 #ifdef MAC 1666 if ((error = mac_proc_check_sched(td->td_ucred, p))) 1667 return (error); 1668 #endif 1669 if ((error = cr_bsd_visible(td->td_ucred, p->p_ucred))) 1670 return (error); 1671 1672 if (td->td_ucred->cr_ruid != p->p_ucred->cr_ruid && 1673 td->td_ucred->cr_uid != p->p_ucred->cr_ruid) { 1674 error = priv_check(td, PRIV_SCHED_DIFFCRED); 1675 if (error) 1676 return (error); 1677 } 1678 return (0); 1679 } 1680 1681 /* 1682 * Handle getting or setting the prison's unprivileged_proc_debug 1683 * value. 1684 */ 1685 static int 1686 sysctl_unprivileged_proc_debug(SYSCTL_HANDLER_ARGS) 1687 { 1688 int error, val; 1689 1690 val = prison_allow(req->td->td_ucred, PR_ALLOW_UNPRIV_DEBUG); 1691 error = sysctl_handle_int(oidp, &val, 0, req); 1692 if (error != 0 || req->newptr == NULL) 1693 return (error); 1694 if (val != 0 && val != 1) 1695 return (EINVAL); 1696 prison_set_allow(req->td->td_ucred, PR_ALLOW_UNPRIV_DEBUG, val); 1697 return (0); 1698 } 1699 1700 /* 1701 * The 'unprivileged_proc_debug' flag may be used to disable a variety of 1702 * unprivileged inter-process debugging services, including some procfs 1703 * functionality, ptrace(), and ktrace(). In the past, inter-process 1704 * debugging has been involved in a variety of security problems, and sites 1705 * not requiring the service might choose to disable it when hardening 1706 * systems. 1707 */ 1708 SYSCTL_PROC(_security_bsd, OID_AUTO, unprivileged_proc_debug, 1709 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_PRISON | CTLFLAG_SECURE | 1710 CTLFLAG_MPSAFE, 0, 0, sysctl_unprivileged_proc_debug, "I", 1711 "Unprivileged processes may use process debugging facilities"); 1712 1713 /*- 1714 * Determine whether td may debug p. 1715 * Returns: 0 for permitted, an errno value otherwise 1716 * Locks: Sufficient locks to protect various components of td and p 1717 * must be held. td must be curthread, and a lock must 1718 * be held for p. 1719 * References: td and p must be valid for the lifetime of the call 1720 */ 1721 int 1722 p_candebug(struct thread *td, struct proc *p) 1723 { 1724 int error, grpsubset, i, uidsubset; 1725 1726 KASSERT(td == curthread, ("%s: td not curthread", __func__)); 1727 PROC_LOCK_ASSERT(p, MA_OWNED); 1728 if (td->td_proc == p) 1729 return (0); 1730 if ((error = priv_check(td, PRIV_DEBUG_UNPRIV))) 1731 return (error); 1732 if ((error = prison_check(td->td_ucred, p->p_ucred))) 1733 return (error); 1734 #ifdef MAC 1735 if ((error = mac_proc_check_debug(td->td_ucred, p))) 1736 return (error); 1737 #endif 1738 if ((error = cr_bsd_visible(td->td_ucred, p->p_ucred))) 1739 return (error); 1740 1741 /* 1742 * Is p's group set a subset of td's effective group set? This 1743 * includes p's egid, group access list, rgid, and svgid. 1744 */ 1745 grpsubset = 1; 1746 for (i = 0; i < p->p_ucred->cr_ngroups; i++) { 1747 if (!groupmember(p->p_ucred->cr_groups[i], td->td_ucred)) { 1748 grpsubset = 0; 1749 break; 1750 } 1751 } 1752 grpsubset = grpsubset && 1753 groupmember(p->p_ucred->cr_rgid, td->td_ucred) && 1754 groupmember(p->p_ucred->cr_svgid, td->td_ucred); 1755 1756 /* 1757 * Are the uids present in p's credential equal to td's 1758 * effective uid? This includes p's euid, svuid, and ruid. 1759 */ 1760 uidsubset = (td->td_ucred->cr_uid == p->p_ucred->cr_uid && 1761 td->td_ucred->cr_uid == p->p_ucred->cr_svuid && 1762 td->td_ucred->cr_uid == p->p_ucred->cr_ruid); 1763 1764 /* 1765 * If p's gids aren't a subset, or the uids aren't a subset, 1766 * or the credential has changed, require appropriate privilege 1767 * for td to debug p. 1768 */ 1769 if (!grpsubset || !uidsubset) { 1770 error = priv_check(td, PRIV_DEBUG_DIFFCRED); 1771 if (error) 1772 return (error); 1773 } 1774 1775 /* 1776 * Has the credential of the process changed since the last exec()? 1777 */ 1778 if ((p->p_flag & P_SUGID) != 0) { 1779 error = priv_check(td, PRIV_DEBUG_SUGID); 1780 if (error) 1781 return (error); 1782 } 1783 1784 /* Can't trace init when securelevel > 0. */ 1785 if (p == initproc) { 1786 error = securelevel_gt(td->td_ucred, 0); 1787 if (error) 1788 return (error); 1789 } 1790 1791 /* 1792 * Can't trace a process that's currently exec'ing. 1793 * 1794 * XXX: Note, this is not a security policy decision, it's a 1795 * basic correctness/functionality decision. Therefore, this check 1796 * should be moved to the caller's of p_candebug(). 1797 */ 1798 if ((p->p_flag & P_INEXEC) != 0) 1799 return (EBUSY); 1800 1801 /* Denied explicitly */ 1802 if ((p->p_flag2 & P2_NOTRACE) != 0) { 1803 error = priv_check(td, PRIV_DEBUG_DENIED); 1804 if (error != 0) 1805 return (error); 1806 } 1807 1808 return (0); 1809 } 1810 1811 /*- 1812 * Determine whether the subject represented by cred can "see" a socket. 1813 * Returns: 0 for permitted, ENOENT otherwise. 1814 */ 1815 int 1816 cr_canseesocket(struct ucred *cred, struct socket *so) 1817 { 1818 int error; 1819 1820 error = prison_check(cred, so->so_cred); 1821 if (error) 1822 return (ENOENT); 1823 #ifdef MAC 1824 error = mac_socket_check_visible(cred, so); 1825 if (error) 1826 return (error); 1827 #endif 1828 if (cr_bsd_visible(cred, so->so_cred)) 1829 return (ENOENT); 1830 1831 return (0); 1832 } 1833 1834 /*- 1835 * Determine whether td can wait for the exit of p. 1836 * Returns: 0 for permitted, an errno value otherwise 1837 * Locks: Sufficient locks to protect various components of td and p 1838 * must be held. td must be curthread, and a lock must 1839 * be held for p. 1840 * References: td and p must be valid for the lifetime of the call 1841 1842 */ 1843 int 1844 p_canwait(struct thread *td, struct proc *p) 1845 { 1846 int error; 1847 1848 KASSERT(td == curthread, ("%s: td not curthread", __func__)); 1849 PROC_LOCK_ASSERT(p, MA_OWNED); 1850 if ((error = prison_check(td->td_ucred, p->p_ucred))) 1851 return (error); 1852 #ifdef MAC 1853 if ((error = mac_proc_check_wait(td->td_ucred, p))) 1854 return (error); 1855 #endif 1856 #if 0 1857 /* XXXMAC: This could have odd effects on some shells. */ 1858 if ((error = cr_bsd_visible(td->td_ucred, p->p_ucred))) 1859 return (error); 1860 #endif 1861 1862 return (0); 1863 } 1864 1865 /* 1866 * Credential management. 1867 * 1868 * struct ucred objects are rarely allocated but gain and lose references all 1869 * the time (e.g., on struct file alloc/dealloc) turning refcount updates into 1870 * a significant source of cache-line ping ponging. Common cases are worked 1871 * around by modifying thread-local counter instead if the cred to operate on 1872 * matches td_realucred. 1873 * 1874 * The counter is split into 2 parts: 1875 * - cr_users -- total count of all struct proc and struct thread objects 1876 * which have given cred in p_ucred and td_ucred respectively 1877 * - cr_ref -- the actual ref count, only valid if cr_users == 0 1878 * 1879 * If users == 0 then cr_ref behaves similarly to refcount(9), in particular if 1880 * the count reaches 0 the object is freeable. 1881 * If users > 0 and curthread->td_realucred == cred, then updates are performed 1882 * against td_ucredref. 1883 * In other cases updates are performed against cr_ref. 1884 * 1885 * Changing td_realucred into something else decrements cr_users and transfers 1886 * accumulated updates. 1887 */ 1888 struct ucred * 1889 crcowget(struct ucred *cr) 1890 { 1891 1892 mtx_lock(&cr->cr_mtx); 1893 KASSERT(cr->cr_users > 0, ("%s: users %d not > 0 on cred %p", 1894 __func__, cr->cr_users, cr)); 1895 cr->cr_users++; 1896 cr->cr_ref++; 1897 mtx_unlock(&cr->cr_mtx); 1898 return (cr); 1899 } 1900 1901 static struct ucred * 1902 crunuse(struct thread *td) 1903 { 1904 struct ucred *cr, *crold; 1905 1906 MPASS(td->td_realucred == td->td_ucred); 1907 cr = td->td_realucred; 1908 mtx_lock(&cr->cr_mtx); 1909 cr->cr_ref += td->td_ucredref; 1910 td->td_ucredref = 0; 1911 KASSERT(cr->cr_users > 0, ("%s: users %d not > 0 on cred %p", 1912 __func__, cr->cr_users, cr)); 1913 cr->cr_users--; 1914 if (cr->cr_users == 0) { 1915 KASSERT(cr->cr_ref > 0, ("%s: ref %ld not > 0 on cred %p", 1916 __func__, cr->cr_ref, cr)); 1917 crold = cr; 1918 } else { 1919 cr->cr_ref--; 1920 crold = NULL; 1921 } 1922 mtx_unlock(&cr->cr_mtx); 1923 td->td_realucred = NULL; 1924 return (crold); 1925 } 1926 1927 static void 1928 crunusebatch(struct ucred *cr, int users, int ref) 1929 { 1930 1931 KASSERT(users > 0, ("%s: passed users %d not > 0 ; cred %p", 1932 __func__, users, cr)); 1933 mtx_lock(&cr->cr_mtx); 1934 KASSERT(cr->cr_users >= users, ("%s: users %d not > %d on cred %p", 1935 __func__, cr->cr_users, users, cr)); 1936 cr->cr_users -= users; 1937 cr->cr_ref += ref; 1938 cr->cr_ref -= users; 1939 if (cr->cr_users > 0) { 1940 mtx_unlock(&cr->cr_mtx); 1941 return; 1942 } 1943 KASSERT(cr->cr_ref >= 0, ("%s: ref %ld not >= 0 on cred %p", 1944 __func__, cr->cr_ref, cr)); 1945 if (cr->cr_ref > 0) { 1946 mtx_unlock(&cr->cr_mtx); 1947 return; 1948 } 1949 crfree_final(cr); 1950 } 1951 1952 void 1953 crcowfree(struct thread *td) 1954 { 1955 struct ucred *cr; 1956 1957 cr = crunuse(td); 1958 if (cr != NULL) 1959 crfree(cr); 1960 } 1961 1962 struct ucred * 1963 crcowsync(void) 1964 { 1965 struct thread *td; 1966 struct proc *p; 1967 struct ucred *crnew, *crold; 1968 1969 td = curthread; 1970 p = td->td_proc; 1971 PROC_LOCK_ASSERT(p, MA_OWNED); 1972 1973 MPASS(td->td_realucred == td->td_ucred); 1974 if (td->td_realucred == p->p_ucred) 1975 return (NULL); 1976 1977 crnew = crcowget(p->p_ucred); 1978 crold = crunuse(td); 1979 td->td_realucred = crnew; 1980 td->td_ucred = td->td_realucred; 1981 return (crold); 1982 } 1983 1984 /* 1985 * Batching. 1986 */ 1987 void 1988 credbatch_add(struct credbatch *crb, struct thread *td) 1989 { 1990 struct ucred *cr; 1991 1992 MPASS(td->td_realucred != NULL); 1993 MPASS(td->td_realucred == td->td_ucred); 1994 MPASS(TD_GET_STATE(td) == TDS_INACTIVE); 1995 cr = td->td_realucred; 1996 KASSERT(cr->cr_users > 0, ("%s: users %d not > 0 on cred %p", 1997 __func__, cr->cr_users, cr)); 1998 if (crb->cred != cr) { 1999 if (crb->users > 0) { 2000 MPASS(crb->cred != NULL); 2001 crunusebatch(crb->cred, crb->users, crb->ref); 2002 crb->users = 0; 2003 crb->ref = 0; 2004 } 2005 } 2006 crb->cred = cr; 2007 crb->users++; 2008 crb->ref += td->td_ucredref; 2009 td->td_ucredref = 0; 2010 td->td_realucred = NULL; 2011 } 2012 2013 void 2014 credbatch_final(struct credbatch *crb) 2015 { 2016 2017 MPASS(crb->cred != NULL); 2018 MPASS(crb->users > 0); 2019 crunusebatch(crb->cred, crb->users, crb->ref); 2020 } 2021 2022 /* 2023 * Allocate a zeroed cred structure. 2024 */ 2025 struct ucred * 2026 crget(void) 2027 { 2028 struct ucred *cr; 2029 2030 cr = malloc(sizeof(*cr), M_CRED, M_WAITOK | M_ZERO); 2031 mtx_init(&cr->cr_mtx, "cred", NULL, MTX_DEF); 2032 cr->cr_ref = 1; 2033 #ifdef AUDIT 2034 audit_cred_init(cr); 2035 #endif 2036 #ifdef MAC 2037 mac_cred_init(cr); 2038 #endif 2039 cr->cr_groups = cr->cr_smallgroups; 2040 cr->cr_agroups = 2041 sizeof(cr->cr_smallgroups) / sizeof(cr->cr_smallgroups[0]); 2042 return (cr); 2043 } 2044 2045 /* 2046 * Claim another reference to a ucred structure. 2047 */ 2048 struct ucred * 2049 crhold(struct ucred *cr) 2050 { 2051 struct thread *td; 2052 2053 td = curthread; 2054 if (__predict_true(td->td_realucred == cr)) { 2055 KASSERT(cr->cr_users > 0, ("%s: users %d not > 0 on cred %p", 2056 __func__, cr->cr_users, cr)); 2057 td->td_ucredref++; 2058 return (cr); 2059 } 2060 mtx_lock(&cr->cr_mtx); 2061 cr->cr_ref++; 2062 mtx_unlock(&cr->cr_mtx); 2063 return (cr); 2064 } 2065 2066 /* 2067 * Free a cred structure. Throws away space when ref count gets to 0. 2068 */ 2069 void 2070 crfree(struct ucred *cr) 2071 { 2072 struct thread *td; 2073 2074 td = curthread; 2075 if (__predict_true(td->td_realucred == cr)) { 2076 KASSERT(cr->cr_users > 0, ("%s: users %d not > 0 on cred %p", 2077 __func__, cr->cr_users, cr)); 2078 td->td_ucredref--; 2079 return; 2080 } 2081 mtx_lock(&cr->cr_mtx); 2082 KASSERT(cr->cr_users >= 0, ("%s: users %d not >= 0 on cred %p", 2083 __func__, cr->cr_users, cr)); 2084 cr->cr_ref--; 2085 if (cr->cr_users > 0) { 2086 mtx_unlock(&cr->cr_mtx); 2087 return; 2088 } 2089 KASSERT(cr->cr_ref >= 0, ("%s: ref %ld not >= 0 on cred %p", 2090 __func__, cr->cr_ref, cr)); 2091 if (cr->cr_ref > 0) { 2092 mtx_unlock(&cr->cr_mtx); 2093 return; 2094 } 2095 crfree_final(cr); 2096 } 2097 2098 static void 2099 crfree_final(struct ucred *cr) 2100 { 2101 2102 KASSERT(cr->cr_users == 0, ("%s: users %d not == 0 on cred %p", 2103 __func__, cr->cr_users, cr)); 2104 KASSERT(cr->cr_ref == 0, ("%s: ref %ld not == 0 on cred %p", 2105 __func__, cr->cr_ref, cr)); 2106 2107 /* 2108 * Some callers of crget(), such as nfs_statfs(), allocate a temporary 2109 * credential, but don't allocate a uidinfo structure. 2110 */ 2111 if (cr->cr_uidinfo != NULL) 2112 uifree(cr->cr_uidinfo); 2113 if (cr->cr_ruidinfo != NULL) 2114 uifree(cr->cr_ruidinfo); 2115 if (cr->cr_prison != NULL) 2116 prison_free(cr->cr_prison); 2117 if (cr->cr_loginclass != NULL) 2118 loginclass_free(cr->cr_loginclass); 2119 #ifdef AUDIT 2120 audit_cred_destroy(cr); 2121 #endif 2122 #ifdef MAC 2123 mac_cred_destroy(cr); 2124 #endif 2125 mtx_destroy(&cr->cr_mtx); 2126 if (cr->cr_groups != cr->cr_smallgroups) 2127 free(cr->cr_groups, M_CRED); 2128 free(cr, M_CRED); 2129 } 2130 2131 /* 2132 * Copy a ucred's contents from a template. Does not block. 2133 */ 2134 void 2135 crcopy(struct ucred *dest, struct ucred *src) 2136 { 2137 2138 KASSERT(dest->cr_ref == 1, ("crcopy of shared ucred")); 2139 bcopy(&src->cr_startcopy, &dest->cr_startcopy, 2140 (unsigned)((caddr_t)&src->cr_endcopy - 2141 (caddr_t)&src->cr_startcopy)); 2142 dest->cr_flags = src->cr_flags; 2143 crsetgroups(dest, src->cr_ngroups, src->cr_groups); 2144 uihold(dest->cr_uidinfo); 2145 uihold(dest->cr_ruidinfo); 2146 prison_hold(dest->cr_prison); 2147 loginclass_hold(dest->cr_loginclass); 2148 #ifdef AUDIT 2149 audit_cred_copy(src, dest); 2150 #endif 2151 #ifdef MAC 2152 mac_cred_copy(src, dest); 2153 #endif 2154 } 2155 2156 /* 2157 * Dup cred struct to a new held one. 2158 */ 2159 struct ucred * 2160 crdup(struct ucred *cr) 2161 { 2162 struct ucred *newcr; 2163 2164 newcr = crget(); 2165 crcopy(newcr, cr); 2166 return (newcr); 2167 } 2168 2169 /* 2170 * Fill in a struct xucred based on a struct ucred. 2171 */ 2172 void 2173 cru2x(struct ucred *cr, struct xucred *xcr) 2174 { 2175 int ngroups; 2176 2177 bzero(xcr, sizeof(*xcr)); 2178 xcr->cr_version = XUCRED_VERSION; 2179 xcr->cr_uid = cr->cr_uid; 2180 2181 ngroups = MIN(cr->cr_ngroups, XU_NGROUPS); 2182 xcr->cr_ngroups = ngroups; 2183 bcopy(cr->cr_groups, xcr->cr_groups, 2184 ngroups * sizeof(*cr->cr_groups)); 2185 } 2186 2187 void 2188 cru2xt(struct thread *td, struct xucred *xcr) 2189 { 2190 2191 cru2x(td->td_ucred, xcr); 2192 xcr->cr_pid = td->td_proc->p_pid; 2193 } 2194 2195 /* 2196 * Change process credentials. 2197 * Callers are responsible for providing the reference for passed credentials 2198 * and for freeing old ones. 2199 * 2200 * Process has to be locked except when it does not have credentials (as it 2201 * should not be visible just yet) or when newcred is NULL (as this can be 2202 * only used when the process is about to be freed, at which point it should 2203 * not be visible anymore). 2204 */ 2205 void 2206 proc_set_cred(struct proc *p, struct ucred *newcred) 2207 { 2208 struct ucred *cr; 2209 2210 cr = p->p_ucred; 2211 MPASS(cr != NULL); 2212 PROC_LOCK_ASSERT(p, MA_OWNED); 2213 KASSERT(newcred->cr_users == 0, ("%s: users %d not 0 on cred %p", 2214 __func__, newcred->cr_users, newcred)); 2215 mtx_lock(&cr->cr_mtx); 2216 KASSERT(cr->cr_users > 0, ("%s: users %d not > 0 on cred %p", 2217 __func__, cr->cr_users, cr)); 2218 cr->cr_users--; 2219 mtx_unlock(&cr->cr_mtx); 2220 p->p_ucred = newcred; 2221 newcred->cr_users = 1; 2222 PROC_UPDATE_COW(p); 2223 } 2224 2225 void 2226 proc_unset_cred(struct proc *p) 2227 { 2228 struct ucred *cr; 2229 2230 MPASS(p->p_state == PRS_ZOMBIE || p->p_state == PRS_NEW); 2231 cr = p->p_ucred; 2232 p->p_ucred = NULL; 2233 KASSERT(cr->cr_users > 0, ("%s: users %d not > 0 on cred %p", 2234 __func__, cr->cr_users, cr)); 2235 mtx_lock(&cr->cr_mtx); 2236 cr->cr_users--; 2237 if (cr->cr_users == 0) 2238 KASSERT(cr->cr_ref > 0, ("%s: ref %ld not > 0 on cred %p", 2239 __func__, cr->cr_ref, cr)); 2240 mtx_unlock(&cr->cr_mtx); 2241 crfree(cr); 2242 } 2243 2244 struct ucred * 2245 crcopysafe(struct proc *p, struct ucred *cr) 2246 { 2247 struct ucred *oldcred; 2248 int groups; 2249 2250 PROC_LOCK_ASSERT(p, MA_OWNED); 2251 2252 oldcred = p->p_ucred; 2253 while (cr->cr_agroups < oldcred->cr_agroups) { 2254 groups = oldcred->cr_agroups; 2255 PROC_UNLOCK(p); 2256 crextend(cr, groups); 2257 PROC_LOCK(p); 2258 oldcred = p->p_ucred; 2259 } 2260 crcopy(cr, oldcred); 2261 2262 return (oldcred); 2263 } 2264 2265 /* 2266 * Extend the passed in credential to hold n items. 2267 */ 2268 void 2269 crextend(struct ucred *cr, int n) 2270 { 2271 int cnt; 2272 2273 /* Truncate? */ 2274 if (n <= cr->cr_agroups) 2275 return; 2276 2277 /* 2278 * We extend by 2 each time since we're using a power of two 2279 * allocator until we need enough groups to fill a page. 2280 * Once we're allocating multiple pages, only allocate as many 2281 * as we actually need. The case of processes needing a 2282 * non-power of two number of pages seems more likely than 2283 * a real world process that adds thousands of groups one at a 2284 * time. 2285 */ 2286 if ( n < PAGE_SIZE / sizeof(gid_t) ) { 2287 if (cr->cr_agroups == 0) 2288 cnt = MAX(1, MINALLOCSIZE / sizeof(gid_t)); 2289 else 2290 cnt = cr->cr_agroups * 2; 2291 2292 while (cnt < n) 2293 cnt *= 2; 2294 } else 2295 cnt = roundup2(n, PAGE_SIZE / sizeof(gid_t)); 2296 2297 /* Free the old array. */ 2298 if (cr->cr_groups != cr->cr_smallgroups) 2299 free(cr->cr_groups, M_CRED); 2300 2301 cr->cr_groups = malloc(cnt * sizeof(gid_t), M_CRED, M_WAITOK | M_ZERO); 2302 cr->cr_agroups = cnt; 2303 } 2304 2305 /* 2306 * Copy groups in to a credential, preserving any necessary invariants. 2307 * Currently this includes the sorting of all supplemental gids. 2308 * crextend() must have been called before hand to ensure sufficient 2309 * space is available. 2310 */ 2311 static void 2312 crsetgroups_locked(struct ucred *cr, int ngrp, gid_t *groups) 2313 { 2314 int i; 2315 int j; 2316 gid_t g; 2317 2318 KASSERT(cr->cr_agroups >= ngrp, ("cr_ngroups is too small")); 2319 2320 bcopy(groups, cr->cr_groups, ngrp * sizeof(gid_t)); 2321 cr->cr_ngroups = ngrp; 2322 2323 /* 2324 * Sort all groups except cr_groups[0] to allow groupmember to 2325 * perform a binary search. 2326 * 2327 * XXX: If large numbers of groups become common this should 2328 * be replaced with shell sort like linux uses or possibly 2329 * heap sort. 2330 */ 2331 for (i = 2; i < ngrp; i++) { 2332 g = cr->cr_groups[i]; 2333 for (j = i-1; j >= 1 && g < cr->cr_groups[j]; j--) 2334 cr->cr_groups[j + 1] = cr->cr_groups[j]; 2335 cr->cr_groups[j + 1] = g; 2336 } 2337 } 2338 2339 /* 2340 * Copy groups in to a credential after expanding it if required. 2341 * Truncate the list to (ngroups_max + 1) if it is too large. 2342 */ 2343 void 2344 crsetgroups(struct ucred *cr, int ngrp, gid_t *groups) 2345 { 2346 2347 if (ngrp > ngroups_max + 1) 2348 ngrp = ngroups_max + 1; 2349 2350 crextend(cr, ngrp); 2351 crsetgroups_locked(cr, ngrp, groups); 2352 } 2353 2354 /* 2355 * Get login name, if available. 2356 */ 2357 #ifndef _SYS_SYSPROTO_H_ 2358 struct getlogin_args { 2359 char *namebuf; 2360 u_int namelen; 2361 }; 2362 #endif 2363 /* ARGSUSED */ 2364 int 2365 sys_getlogin(struct thread *td, struct getlogin_args *uap) 2366 { 2367 char login[MAXLOGNAME]; 2368 struct proc *p = td->td_proc; 2369 size_t len; 2370 2371 if (uap->namelen > MAXLOGNAME) 2372 uap->namelen = MAXLOGNAME; 2373 PROC_LOCK(p); 2374 SESS_LOCK(p->p_session); 2375 len = strlcpy(login, p->p_session->s_login, uap->namelen) + 1; 2376 SESS_UNLOCK(p->p_session); 2377 PROC_UNLOCK(p); 2378 if (len > uap->namelen) 2379 return (ERANGE); 2380 return (copyout(login, uap->namebuf, len)); 2381 } 2382 2383 /* 2384 * Set login name. 2385 */ 2386 #ifndef _SYS_SYSPROTO_H_ 2387 struct setlogin_args { 2388 char *namebuf; 2389 }; 2390 #endif 2391 /* ARGSUSED */ 2392 int 2393 sys_setlogin(struct thread *td, struct setlogin_args *uap) 2394 { 2395 struct proc *p = td->td_proc; 2396 int error; 2397 char logintmp[MAXLOGNAME]; 2398 2399 CTASSERT(sizeof(p->p_session->s_login) >= sizeof(logintmp)); 2400 2401 error = priv_check(td, PRIV_PROC_SETLOGIN); 2402 if (error) 2403 return (error); 2404 error = copyinstr(uap->namebuf, logintmp, sizeof(logintmp), NULL); 2405 if (error != 0) { 2406 if (error == ENAMETOOLONG) 2407 error = EINVAL; 2408 return (error); 2409 } 2410 AUDIT_ARG_LOGIN(logintmp); 2411 PROC_LOCK(p); 2412 SESS_LOCK(p->p_session); 2413 strcpy(p->p_session->s_login, logintmp); 2414 SESS_UNLOCK(p->p_session); 2415 PROC_UNLOCK(p); 2416 return (0); 2417 } 2418 2419 void 2420 setsugid(struct proc *p) 2421 { 2422 2423 PROC_LOCK_ASSERT(p, MA_OWNED); 2424 p->p_flag |= P_SUGID; 2425 } 2426 2427 /*- 2428 * Change a process's effective uid. 2429 * Side effects: newcred->cr_uid and newcred->cr_uidinfo will be modified. 2430 * References: newcred must be an exclusive credential reference for the 2431 * duration of the call. 2432 */ 2433 void 2434 change_euid(struct ucred *newcred, struct uidinfo *euip) 2435 { 2436 2437 newcred->cr_uid = euip->ui_uid; 2438 uihold(euip); 2439 uifree(newcred->cr_uidinfo); 2440 newcred->cr_uidinfo = euip; 2441 } 2442 2443 /*- 2444 * Change a process's effective gid. 2445 * Side effects: newcred->cr_gid will be modified. 2446 * References: newcred must be an exclusive credential reference for the 2447 * duration of the call. 2448 */ 2449 void 2450 change_egid(struct ucred *newcred, gid_t egid) 2451 { 2452 2453 newcred->cr_groups[0] = egid; 2454 } 2455 2456 /*- 2457 * Change a process's real uid. 2458 * Side effects: newcred->cr_ruid will be updated, newcred->cr_ruidinfo 2459 * will be updated, and the old and new cr_ruidinfo proc 2460 * counts will be updated. 2461 * References: newcred must be an exclusive credential reference for the 2462 * duration of the call. 2463 */ 2464 void 2465 change_ruid(struct ucred *newcred, struct uidinfo *ruip) 2466 { 2467 2468 (void)chgproccnt(newcred->cr_ruidinfo, -1, 0); 2469 newcred->cr_ruid = ruip->ui_uid; 2470 uihold(ruip); 2471 uifree(newcred->cr_ruidinfo); 2472 newcred->cr_ruidinfo = ruip; 2473 (void)chgproccnt(newcred->cr_ruidinfo, 1, 0); 2474 } 2475 2476 /*- 2477 * Change a process's real gid. 2478 * Side effects: newcred->cr_rgid will be updated. 2479 * References: newcred must be an exclusive credential reference for the 2480 * duration of the call. 2481 */ 2482 void 2483 change_rgid(struct ucred *newcred, gid_t rgid) 2484 { 2485 2486 newcred->cr_rgid = rgid; 2487 } 2488 2489 /*- 2490 * Change a process's saved uid. 2491 * Side effects: newcred->cr_svuid will be updated. 2492 * References: newcred must be an exclusive credential reference for the 2493 * duration of the call. 2494 */ 2495 void 2496 change_svuid(struct ucred *newcred, uid_t svuid) 2497 { 2498 2499 newcred->cr_svuid = svuid; 2500 } 2501 2502 /*- 2503 * Change a process's saved gid. 2504 * Side effects: newcred->cr_svgid will be updated. 2505 * References: newcred must be an exclusive credential reference for the 2506 * duration of the call. 2507 */ 2508 void 2509 change_svgid(struct ucred *newcred, gid_t svgid) 2510 { 2511 2512 newcred->cr_svgid = svgid; 2513 } 2514 2515 bool allow_ptrace = true; 2516 SYSCTL_BOOL(_security_bsd, OID_AUTO, allow_ptrace, CTLFLAG_RWTUN, 2517 &allow_ptrace, 0, 2518 "Deny ptrace(2) use by returning ENOSYS"); 2519